Comparison of Late Neogene U k′ 37 and TEX 86 Paleotemperature Records From the Eastern Equatorial Pacific at Orbital Resolution
Comparison of Late Neogene U k′ 37 and TEX 86 Paleotemperature Records From the Eastern Equatorial Pacific at Orbital Resolution
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东赤道太平洋新近纪晚期 U kâ2 37 和 TEX 86 古温度记录在轨道分辨率上的比较
DOI：
10.1029/2020pa003858
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发表时间：
2020
影响因子：
3.5
通讯作者：
Lawrence, C. E.
中科院分区：
文献类型：
--
作者：
Lawrence, K. T.;Pearson, A.;Castañeda, I. S.;Ladlow, C.;Peterson, L. C.;Lawrence, C. E.
晚新近纪气候的主要特征仍然不确定，由于来自不同的海表温度（SST）代理的相互冲突的记录。为了理解代理衍生温度估计值可以互换使用或测量同一系统的不同方面的情况，有必要探索特定古温度计之间的差异和差异。在这里，我们报告的轨道尺度气候记录ODP站点846在赤道东太平洋（EEP）的时间间隔从~5-6 Ma的烯酮和古脂古温度计。两个代理的结果在长期趋势和长期温度变化的幅度方面是相似的，光谱分析表明，记录在双折射和岁差带中是一致的和同相的。然而，我们发现TEX 86重建的温度在全球校准中相对于Uk′37导出的温度一致地向更冷的值偏移约2 °C，或者在基于贝叶斯的校准中偏移约0.8 °C。所有的校准组合也产生了大约两倍的TEX 86轨道尺度变化的幅度相对于Uk′37导出的温度波动。这两个温度代理呈负相关的沉积烯酮浓度，我们使用的出口生产力增加的指标。从TEX 86中去除这种生产率贡献，得到了调整后的TEX 86记录，其温度灵敏度与Uk′37相同。在未来的应用中，这个信号可能会解耦使用额外的沉积指标的古生产力，这可能是最重要的上升流区环境。还有其他一些无法解释的因素导致了TEX 86和Uk′ 37之间的差异，需要进一步的研究。
Key features of late Neogene climate remain uncertain due to conflicting records derived from different sea surface temperature (SST) proxies. To understand scenarios in which proxy‐derived temperature estimates can be used interchangeably or are instead measuring different aspects of the same system, it is necessary to explore both the consistencies and differences between specific paleothermometers. Here, we report orbital‐scale climate records from ODP Site 846 in the eastern equatorial Pacific (EEP) for the interval from ~5–6 Ma using alkenone and archaeal lipid paleothermometers. Results from both proxies are similar in their secular trends and magnitude of long‐term temperature change, and spectral analysis demonstrates that the records are coherent and in‐phase in both the obliquity and precession bands. However, we find that the temperatures reconstructed by TEX86are consistently offset toward colder values by ~2 °C relative to Uk′37‐derived temperatures in global calibrations, or by ~0.8 °C in Bayesian‐based calibrations. All combinations of calibrations also yield approximately twice the amplitude of orbital‐scale variation in TEX86relative to Uk′37‐derived temperature fluctuations. Both temperature proxies are negatively correlated with sedimentary alkenone concentrations, which we use as an indicator of increased export productivity. Removing this productivity contribution from TEX86results in an adjusted TEX86record with temperature sensitivity identical to Uk′37. In future applications, this signal may be decoupled using additional sedimentary indicators of paleoproductivity, which likely will be most important for upwelling zone environments. There remain other nonexplained factors that contribute to differences between TEX86and Uk′37that warrant additional investigation.